1. Field of the Invention
The present invention relates to a bending operation device for an endoscope provided in an operation section of the endoscope that bends a bending portion provided in an insertion portion of the endoscope and to the endoscope.
2. Description of the Related Art
In recent years, endoscopes are widely used in a medical field and an industrial field. With the endoscope used in the medical field, it is possible to observe organs in a body cavity, which is an object to be examined, by inserting an elongated insertion portion into the body cavity and to perform various kinds of treatment according to necessity using a treatment instrument inserted into an insertion channel for the treatment instrument included in the endoscope.
With the endoscope used in the industrial field, it is possible to perform observations of scratches, corrosions, and the like of a region to be examined in an object to be examined such as inside a jet engine or piping of a factory and inspections such as various kinds of treatment by inserting an elongated insertion portion of the endoscope into the object to be examined.
A configuration is well known in which a bending portion bendable in plural directions is provided in the insertion portion of the endoscope. The bending portion improves progress properties of the insertion portion in a bent portion in a conduit. Besides, the bending portion changes, in the insertion portion, an observation direction of an observation optical system provided at a distal end portion located further on a distal end side in an inserting direction than the bending portion.
Usually, plural bending pieces are coupled along an inserting direction of the insertion portion, whereby the bending portion provided in the insertion portion of the endoscope is configured to be bendable, for example, in up, down, left, and right four directions. Any one of four wires inserted through the insertion portion, a distal end of which is fixed to the bending piece located most on the distal end side in the inserting direction among the bending pieces, is dragged by a bending operation device provided in an operation section, whereby the bending portion is bendable in any one of the up, down, left, and right directions.
Specifically, the bending portion has a configuration in which a bending operation knob for up and down bending provided in the operation section is operated to pivot, whereby a sprocket for up and down bending provided in the operation section is caused to pivot, and one of an upper chain region and a lower chain region of a chain for up and down bending wound around the sprocket is dragged, whereby the bending portion is bent in an up or down direction.
Further, the bending portion has a configuration in which a bending operation knob for left and right bending provided in the operation section is operated to pivot, whereby a sprocket for left and right bending provided in the operation section is caused to pivot, and one of a left chain region and a right chain region of a chain for left and right bending wound around the sprocket is dragged, whereby the bending portion is bent in a left or right direction.
A configuration is also well known in which the operation section is provided with a lock lever for up and down that fixes a bending angle of the bending portion bent in the up direction or the down direction by the pivoting operation of the bending operation knob for up and down bending, i.e., a pivoting position of the bending operation knob for up and down bending and a lock knob for left and right that fixes a bending angle of the bending portion bent in the left direction or the right direction by the pivoting operation of the bending operation knob for left and right bending, i.e., a pivoting position of the bending operation knob for left and right bending. The configuration is disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 10-286220.
Japanese Patent Application Laid-Open Publication No. 10-286220 discloses a configuration in which a friction member that comes into contact with an inner circumferential surface of the knob and a movable member and a fixed member that can hold the friction member are provided in a space in the bending operation knob for up and down bending. The movable member is fixed to the lock lever for up and down.
When the pivoting position of the bending operation knob for up and down bending is fixed using the configuration disclosed in Japanese Patent Application Laid-Open Publication No. 10-286220, the lock lever for up and down is rotated in one direction and the movable member is rotated in one direction together with the lock lever, whereby the movable member is moved with respect to the fixed member using a screw mechanism, and the friction member is held between the fixed member and the movable member to elastically deform the friction member and the friction member is brought into contact with the inner circumferential surface of the bending operation knob for up and down bending using a friction force, whereby the pivoting position of the bending operation knob for up and down bending is fixed by the friction force.
In Japanese Patent Application Laid-Open Publication No. 10-286220, a configuration for fixing the pivoting position of the bending operation knob for left and right bending has a configuration same as the configuration for fixing the pivoting position of the bending operation knob for up and down bending.
The present invention has been devised in view of the circumstances explained above and it is an object of the present invention to provide a bending operation device for an endoscope including a configuration that can surely fix, with an operation force smaller than that in the past, a pivoting position of a bending operation knob without variations every time the bending operation device is used and provide the endoscope.